Psychological Science
October
2006 (Volume 17, Issue 10 Page 825-924) View
Issue
Research Reports
Decoupling Neural Networks From Reality: Dissociative Experiences in Torture Victims Are Reflected in Abnormal Brain Waves in Left Frontal Cortex
William J. Ray, Michael Odenwald, Frank Neuner, Maggie Schauer, Martina Ruf, Christian Wienbruch, Brigitte Rockstroh, and Thomas Elbert
This study examined the role of verbal labeling in 4-year-old children's acquisition of action-effect learning. The acquisition of action-effect associations was tested by having children first perform a two-choice key-pressing task in which each key press was followed by an effect (i.e., a particular sound) and then respond to the previously perceived effects under either consistent or inconsistent key-sound mappings. During acquisition, the children overtly described the actions, the effects, both the actions and the effects, or, in a control condition, something irrelevant to the actions and effects. Action-effect learning was reliable only if the description related actions to effects, even though some evidence of learning was also obtained in the control condition. In contrast, learning was prevented if only the actions or only the effects were described. The results suggest that verbal labeling plays an important role in integrating and isolating event representations.
Preferences for mates that possess genes dissimilar to one's own at the major histocompatibility complex (MHC), a polymorphic group of loci associated with the immune system, have been found in mice, birds, fish, and humans. These preferences may help individuals choose genetically compatible mates and may adaptively function to prevent inbreeding or to increase heterozygosity and thereby immunocompetence of offspring. MHC-dissimilar mate preferences may influence the psychology of sexual attraction. We investigated whether MHC similarity among romantically involved couples (N = 48) predicted aspects of their sexual relationship. All women in our sample normally ovulated, and alleles at three MHC loci were typed for each person. As the proportion of MHC alleles couples shared increased, women's sexual responsivity to their partners decreased, their number of extrapair sexual partners increased, and their attraction to men other than their primary partners increased, particularly during the fertile phase of their cycles.
People often find it more difficult to distinguish ethnic out-group members compared with ethnic in-group members. A functional approach to social cognition suggests that this bias may be eliminated when out-group members display threatening facial expressions. In the present study, 192 White participants viewed Black and White faces displaying either neutral or angry expressions and later attempted to identify previously seen faces. Recognition accuracy for neutral faces showed the out-group homogeneity bias, but this bias was entirely eliminated for angry Black faces. Indeed, when participants' cognitive processing capacity was constrained, recognition accuracy was greater for angry Black faces than for angry White faces, demonstrating an out-group heterogeneity bias.
Is Belief Reasoning Automatic?
Understanding the operating characteristics of theory of mind is essential for understanding how beliefs, desires, and other mental states are inferred, and for understanding the role such inferences could play in other cognitive processes. We present the first investigation of the automaticity of belief reasoning. In an incidental false-belief task, adult subjects responded more slowly to unexpected questions concerning another person's belief about an object's location than to questions concerning the object's real location. Results in other conditions showed that responses to belief questions were not necessarily slower than responses to reality questions, as subjects showed no difference in response times to belief and reality questions when they were instructed to track the person's beliefs about the object's location. The results suggest that adults do not ascribe beliefs to agents automatically.
Short Report
Research Articles
Dehumanizing the Lowest of the Low: Neuroimaging Responses to Extreme Out-Groups
Traditionally, prejudice has been conceptualized as simple animosity. The stereotype content model (SCM) shows that some prejudice is worse. The SCM previously demonstrated separate stereotype dimensions of warmth (low-high) and competence (low-high), identifying four distinct out-group clusters. The SCM predicts that only extreme out-groups, groups that are both stereotypically hostile and stereotypically incompetent (low warmth, low competence), such as addicts and the homeless, will be dehumanized. Prior studies show that the medial prefrontal cortex (mPFC) is necessary for social cognition. Functional magnetic resonance imaging provided data for examining brain activations in 10 participants viewing 48 photographs of social groups and 12 participants viewing objects; each picture dependably represented one SCM quadrant. Analyses revealed mPFC activation to all social groups except extreme (low-low) out-groups, who especially activated insula and amygdala, a pattern consistent with disgust, the emotion predicted by the SCM. No objects, though rated with the same emotions, activated the mPFC. This neural evidence supports the prediction that extreme out-groups may be perceived as less than human, or dehumanized.
Fitting in Matters: Markers of In-Group Belonging and Academic Outcomes
Minority boys are at risk of academic disengagement. Prior research documents that an aspect of racial-ethnic identity, in-group connection, can buffer against this risk, but that in-group connection is undermined in high-risk neighborhoods. We examined another way that boys may feel connected to the in-group, by looking like in-group members. We hypothesize that physical markers of in-group membership can serve to improve boys' sense of belongingness, thereby facilitating their engagement in school. We tested our model with low-income, high-risk African American (Study 1, n = 102) and Latino (Study 2, n = 66) teens. Hierarchical regression supported our model; dark skin tone was a protective factor (and light skin tone a risk factor) for African American boys, and feeling that one looks Latino was a protective factor (and feeling that one does not look Latino a risk factor) for Latino boys' grades, in-class behavior, and school engagement. Mediational analyses suggest that markers of belongingness have their impact via peer-group choice.
Although 50 years of research demonstrate that friendly intergroup contact reduces intergroup prejudice, the findings are based solely on self-reported, explicit prejudice. In two parallel experiments examining intergroup contact and prejudice—between Whites and Blacks in the United States (Experiment 1) and between Christians and Muslims in Lebanon (Experiment 2)—we examined whether intergroup status differences moderate contact effects on implicit prejudice, as well as explicit prejudice. Both experiments replicated the standard effect of contact on explicit prejudice. They also demonstrated that intergroup contact reduces implicit prejudice among low-status groups. In Experiment 1, the implicit prejudice of Blacks toward Whites (but not Whites toward Blacks) was reduced as a function of friendly contact. In Experiment 2, the implicit prejudice of Muslims toward Christians (but not Christians toward Muslims) was reduced as a function of friendly contact.
Heterosocial Perceptual Organization: Application of the Choice Model to Sexual Coercion
Luce's (1959, 1963) choice model was used to characterize individual differences in men's perception of women's affect as friendly, sexually interested, sad, or rejecting. Women's clothing styles were associated with differences in the model's parameters. Sensitivity to sadness, rejection, and friendliness declined when women were dressed provocatively, whereas sensitivity to sexual interest increased. Provocative clothing was also associated with an increased bias to assume that positive affect was sexual interest rather than friendliness. Men at risk for perpetrating sexual aggression were less sensitive to women's affect than low-risk men were. They were also more likely than low-risk men to associate provocative clothing with sexual interest, and conservative clothing with friendliness. Results indicate that heterosocial perception may help to predict sexually coercive behavior and may be an important target for intervention.
A perceptually filled-in surface, such as occurs during sustained attention to a peripheral stimulus (Troxler fading), can be functionally equivalent to a physically presented stimulus. Observers failed to detect probes that were presented in the location of a filled-in surface that had the same surface attributes as the probes; this was true even though, physically, the probes contrasted with the background. Probe stimuli with surface characteristics different from those of the filled-in surface were detected more often, though not quite as often as when there was no filled-in surface. Together, these findings support the idea that there are two components in perceptual filling: a neural filling-in component and a sustained-attention component, which actively suppresses perceptual processing at the filled-in location. More broadly, they illustrate the interplay of basic visual mechanisms in the creation and representation of visual surfaces and in the coding and detection of changes to these surfaces.
Insight occurs when problem solutions arise suddenly and seem obviously correct, and is associated with an "Aha!" experience. Prior theorizing concerning preparation that facilitates insight focused on solvers' problem-specific knowledge. We hypothesized that a distinct type of mental preparation, manifested in a distinct brain state, would facilitate insight problem solving independently of problem-specific knowledge. Consistent with this hypothesis, neural activity during a preparatory interval before subjects saw verbal problems predicted which problems they would subsequently solve with, versus without, self-reported insight. Specifically, electroencephalographic topography and frequency (Experiment 1) and functional magnetic resonance imaging signal (Experiment 2) both suggest that mental preparation leading to insight involves heightened activity in medial frontal areas associated with cognitive control and in temporal areas associated with semantic processing. The results for electroencephalographic topography suggest that noninsight preparation, in contrast, involves increased occipital activity consistent with an increase in externally directed visual attention. Thus, general preparatory mechanisms modulate problem-solving strategy.
Sleep Facilitates Consolidation of Emotional Declarative Memory
Both sleep and emotion are known to modulate processes of memory consolidation, yet their interaction is poorly understood. We examined the influence of sleep on consolidation of emotionally arousing and neutral declarative memory. Subjects completed an initial study session involving arousing and neutral pictures, either in the evening or in the morning. Twelve hours later, after sleeping or staying awake, subjects performed a recognition test requiring them to discriminate between these original pictures and novel pictures by responding "remember," "know" (familiar), or "new." Selective sleep effects were observed for consolidation of emotional memory: Recognition accuracy for know judgments of arousing stimuli improved by 42% after sleep relative to wake, and recognition bias for remember judgments of these stimuli increased by 58% after sleep relative to wake (resulting in more conservative responding). These findings hold important implications for understanding of human memory processing, suggesting that the facilitation of memory for emotionally salient information may preferentially develop during sleep.
Choosing an Inferior Alternative
We show how decision makers can be induced to choose a personally inferior alternative, a strong violation of rational decision making. First, the inferior alternative is installed as the leading option by starting with information that supports this alternative. Then, the decision maker uses the natural process of distorting new information to support whichever alternative is leading. This leader-supporting distortion overcomes the inherent advantages of the superior alternative. The end result is a tendency to choose the self-identified inferior alternative. We trace the choice process to reveal the amount of distortion and its influence on preference. Self-reported awareness of distortion to support the inferior alternative is not related to the amount of distortion. The absence of valid awareness suggests that the manipulation that produces this preference violation is unlikely to be detected and that the distortion is unlikely to be corrected by the decision maker. As expected, given the lack of awareness, final confidence is just as high when the inferior alternative is chosen as when the superior one is. The discussion considers how to prevent an adversary from manipulating one's decisions using this technique.
When learners encode sequential patterns and generalize their knowledge to novel instances, are they relying on abstract or stimulus-specific representations? Research on artificial grammar learning (AGL) has shown transfer of learning from one stimulus set to another, and such findings have encouraged the view that statistical learning is mediated by abstract representations that are independent of the sense modality or perceptual features of the stimuli. Using a novel modification of the standard AGL paradigm, we obtained data to the contrary. These experiments pitted abstract processing against stimulus-specific learning. The findings show that statistical learning results in knowledge that is stimulus-specific rather than abstract. They show furthermore that learning can proceed in parallel for multiple input streams along separate perceptual dimensions or sense modalities. We conclude that learning sequential structure and generalizing to novel stimuli inherently involve learning mechanisms that are closely tied to the perceptual characteristics of the input.
Black Americans Reduce the Racial IQ Gap: Evidence From Standardization Samples
It is often asserted that Black Americans have made no IQ gains on White Americans. Until recently, there have been no adequate data to measure trends in Black IQ. We analyzed data from nine standardization samples for four major tests of cognitive ability. These data suggest that Blacks gained 4 to 7 IQ points on non-Hispanic Whites between 1972 and 2002. Gains have been fairly uniform across the entire range of Black cognitive ability.
Commentaries